1. Field of the Invention
The present invention belongs to the technical field of engineering machinery, and particularly relates to a load-adaptive hoisting mechanism.
2. The Prior Arts
The hoisting mechanism is an important operating part of a lot of engineering machinery. In order to meet high load demands, the hoisting speed of the hoisting mechanism commonly used in conventional hoists, freight elevators and other machinery sometimes needs to be reduced. However, in that case, even if the actual load is changed to be lighter, the hoisting speed cannot be correspondingly increased. In order to meet requirements for both speed and torque, according to conventional methods, usually the motor power is increased, but an adaptive adjusting mechanism for speed and torque is lacked. In order to solve the problem of adjusting hoisting speed and hoisting force, a continuously variable transmission mechanism or a servo motor is adopted in a commonly used method. However, the conventional continuously variable transmission mechanism adopts the complex structure and usually uses a large hydraulic system in a large size as a power source, and the servo motor also requires electronic control and other aided mechanisms for a speed adjustment process, so that maintenance and repair are difficult and the cost is high.
The decelerating mechanism commonly used in the conventional robotic joint and tension-compression apparatus has a constant transmission ratio and the output speed cannot be flexibly adjusted, so that the using range is limited. Robot hands' grasping motion driven by the common hoisting mechanism encounters two opposite problems: the first one: if the grasping speed is high, the target is difficult to grasp tightly due to the constant hoisting force, and therefore the target can slip off; in contrast, if the grasping speed becomes lower, the increased hoisting force can enable the target to be tightly grasped, however the efficiency is reduced.
Currently in the mechanical field, the situation that a transmission mechanism automatically adjusts the output force according to the loads can be realized usually by electrification auxiliary control; the structure is complex, the reliability is poor and applicability is limited, so that very few purely mechanical automatically load-adaptive transmission mechanisms exist in the market.